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  1. #1
    Seaman
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    Default Ethanol Fuel Seperation Problems

    I suspect that I have an ethanol seperation problem. My engine dies under hard acceleration so I drained the carb bowl, collected the fuel into a glass jar. There is definatley two seperate layers in the fuel. After reading several posts online, I suspect ethanol seperation. How can this be confirmed? How can this be remedied? Will fuel treatment or fuel drier break the fuel up so it can be burned? Any advice is appreciated. Thanks a million.

  2. #2
    Moderator Bob_VT's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Just about any old fuel will go bad.

    Install a fuel/water separator.

    Usually people drain older/bad fuel and use it to mow their lawns.
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  3. #3

    Default Re: Ethanol Fuel Seperation Problems

    The bottom "layer" you see is water (or mostly water). As already mentioned get rid of the bad fuel, install a fuel/water separator, and start adding fuel treatment every time you buy fuel.

  4. #4
    Chief Petty Officer jmarty10's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    I'm curious about how old your fuel is. There doesnt seem to be a good answer on what the time frame is about when water seperation occurs in ethanol fuel. Right now, I have marine gas with val-tech that is 3 weeks old. Have about a half tank now and when I first filled tank I put stabil in (red stuff). The remaining gas will be burned on Saturday.

  5. #5
    Supreme Mariner Silvertip's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    You prevent separation by using the fuel before it separates. You protect the fuel by using a fuel system treatment of which there are many (Stabil and SeaFoam to name just two). Adding a water separating fuel filter is very important.

  6. #6
    Lieutenant Commander 109jb's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Th fuel will not separate unless there is water in there also. Water can get in obviously by a leak, bad supply, or from condensation forming on the interior of the tank. You can prevent this condensation by keeping the fuel tank full. This keeps air out of the tank. Humid moisture laden air that cools is the source of the condensation.

  7. #7
    Admiral dingbat's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    If its phase separation its a mixture of water and alcohol. Throw the concoction in a bucket of water. If it's phase the fluid will turn white when it comes in contact with the water.

    Gasoline and alcohol will not separate over time and you can not condensate enough moisture out of the air to cause phase. The only way separation occurs is if you have free water in your tank. You left the cap off, water got in thru the vent or you where “dosed” at a filling station.

    Contrary to what the additive salesmen wants you to believe, there is no additive that will prevent phase and there is no additive to repair it. If you have a large quantity of free water in the tank the only solution is to remove it. You can drain the tank, or siphon the water off the bottom of the tank if you have a large tank, but you need to get the free water out of the tank if you want to mitigate the problem correctly.
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  8. #8

    Default Re: Ethanol Fuel Seperation Problems

    I can not believe how lucky I have it here in SW MO. Several gas stations around here have ethanol free premium, 20 to 30 cents more than premium blended w ethanol. Well worth the cost. Run it in all my small engines, especially the 2 strokes.

  9. #9
    Seaman
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    Default Re: Ethanol Fuel Seperation Problems

    I filled my tank with high octane fuel last November and added the recomended amount of fuel stabilizer. The boat was dry docked and stored indoors. I am certain there is no chance that water introduced to the fuel system. I ran it for the first time on July 2nd and encountered poor performance above 25mph. Like I mentioned, the boat starts right up and idles however will not run at higher speeds. The gas does not stink like it is bad. All I know is I will not purchase any more of that brand of fuel.

  10. #10
    Lieutenant Commander 109jb's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by dingbat View Post
    ... and you can not condensate enough moisture out of the air to cause phase. ...
    I disagree. It depends on the venting of the tank and the amount of air space in the tank. A vented tank with a lot of air space and not a lot of fuel in it can condense enough water to cause separation. It doesn't happen overnight, but if it has been sitting a long time it can and does happen.

  11. #11
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    Default Re: Ethanol Fuel Seperation Problems

    If you start good, idle good and run good below 25 and not above 25 mph, I think you need to look at something besides bad fuel, bad fuel should give performance problems at all operating points. You may have low fuel pressure, fuel filter stopped up, if you had that much water in fuel you probably would not start.
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  12. #12
    Chief Petty Officer jmarty10's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Litewin - try a small fix first like changing your water seperator and draining the gas and replacing with fresh gas. Becasue I am interested in this issue I have seen posts where guys hook up a small 6 gallon portable fuel tank to start diagnosing. But, the easiest fix may be the water seperator?

  13. #13
    Admiral dingbat's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by 109jb View Post
    I disagree. It depends on the venting of the tank and the amount of air space in the tank. A vented tank with a lot of air space and not a lot of fuel in it can condense enough water to cause separation. It doesn't happen overnight, but if it has been sitting a long time it can and does happen.
    It is highly unlikely according to these two EPA memos and numerous other studies I've read.

    Since the solubility of water in both gasoline and air decreases with a decrease in temperature, water can enter a fuel system through condensation when the atmospheric temperature changes. For example, assume a tank containing conventional gasoline contains only one gallon of fuel. Assume also that it is closed while the outside temperature is 100 degrees F with a relative humidity of 100 percent. If this tank is left sealed and the temperature drops to 40 degrees F, water will likely condense on the inside of the tank, and dissolve in the fuel. In order for enough water to condense from the air to cause gasoline-water phase separation, however, there must be approximately 200 gallons of air per gallon of fuel over this temperature drop (100 to 40 degrees). Since oxygenated fuels can hold even more water than conventional gasoline, it is even more unlikely that enough water will condense from the air to cause gasoline-water phase separation.

    Water, in the form of water vapor, can dissolve in gasoline. The more humid the air, the faster the water vapor will dissolve in the gasoline. Due to chemical equilibrium, however, assuming a constant temperature, phase separation will never occur if the only source of water is from the air. Only enough water to saturate the fuel can enter the system, and no more. Water vapor, however, dissolves in gasoline very slowly, even at very high humidity. For example, at a constant temperature of 100 degrees F and relative humidity of 100%, it would take well over 200 days to saturate one gallon of gasoline in an open gasoline can (assuming the only source of water is water vapor from the air). Water absorption from the air is far slower at lower temperatures and humidity. (At a temperature of 70 degrees and relative humidity of 70%, it would take over two years to saturate one gallon of conventional gasoline in the same gasoline can.) Again, oxygenated gasoline can hold more water than conventional gasoline, and would therefore take much longer to saturate with water.
    http://www.epa.gov/oms/regs/fuels/rfg/waterphs.pdf

    Some manufacturers have expressed concern that ethanol-blended gasolines might absorb water vapor from the atmosphere, leading to phase separation. Such problems are of greatest concern for engines with open-vented fuel tanks that are operated in humid environments, such as marine engines. However, evidence for this phenomenon occurring is limited at best. States with extensive ethanol programs, such as Minnesota, have not reported problems with phase separation due to absorption of water from the atmosphere.

    Limited testing with ethanol blends suggests that the rate of water absorption from the atmosphere is very slow; it requires several months for open-vented marine fuel tanks to accumulate sufficient water to make phase separation possible, and another source of water is needed before separation will actually occur. Of far greater concern is the accidental introduction of water, by splash or spray, during fueling or the presence of water in the fuel
    tank prior to the addition of ethanol-blended gasolines.
    http://www.epa.gov/oms/regs/fuels/ostp-3.pdf
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  14. #14
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    Default Re: Ethanol Fuel Seperation Problems

    If you don't let any water into your tank then you won't get any condensation in it.

  15. #15
    Seaman
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    Default Re: Ethanol Fuel Seperation Problems

    The gas sample is definitely seperated with milky colored water. I will siphon the fuel out this weekend and install a water separator. (Filter type with a clear water trap on the bottom)

    All of the fuel system components are new including a complete carb rebuild and the system function was confirmed to be ok.

    My system has two fuel pumps, an electric fuel pump serves as a booster to the main mechanical fuel pump on the engine. So no problems with fuel pressure. (8psi at the fuel inlet to the carb)

    The boat will idle ok but however will not operate when fuel demand is high. Keep in mind the main jets and power valve are located at the bottom of the fuel bowl where the water settles. So when fuel demand is high, water is ingested instead of gas.

    I will make the updates, test the boat and let everyone know if there is a happy ending.

    Thanks for all of the great feedback.

  16. #16
    Lieutenant Commander Beefer's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by Fed View Post
    If you don't let any water into your tank then you won't get any condensation in it.
    You do realize that air contains moisture, and your fuel tank has a vent which not only allows air in, but pulls it in, don't you?
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  17. #17
    Lieutenant Commander Beefer's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by 109jb View Post
    I disagree. It depends on the venting of the tank and the amount of air space in the tank. A vented tank with a lot of air space and not a lot of fuel in it can condense enough water to cause separation. It doesn't happen overnight, but if it has been sitting a long time it can and does happen.
    I agree with this post. Phase separation will occur at 0.5% water in fuel. So, (and the math will be really really rough), if you have a 100 gal tank, with 20 gals of fuel in it, you will have 80 gals of air by volume, or roughly 1 cubic meter (probably not too far off for a 100 gal tank at 20% capacity). With a humidity level of let's say 50%, at a temp of about 77 deg F (25 C), you will have 11.5 grams of water per cubic meter. When the temp gets down to 55F/13C (dew point), that moisture will condense. After a few weeks/months, it won't take long for the accumulation of 1/10 gal of water (12.8 oz) to occur. At that point, you will then create what is necessary for phase separation to occur.

    And by the way, phase separation can occur as low as 0.3%.
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  18. #18
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    Default Re: Ethanol Fuel Seperation Problems

    80 Gallons is only 0.3028329 cubic metres, how many grams of water can you wring out of that and how many times can you wring it out.
    Of course your arguement assumes the temperature inside the tank drops to the ambient outside temperature as well.

    If condensation was causing water problems inside fuel tanks the seas would be awash with dead boats and the roads would be littered with dead cars.

  19. #19
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    Default Re: Ethanol Fuel Seperation Problems

    E-10 ethanol fuel begins to separate the second it leaves the pump. My current job is working in a small engine shop, and 90% of the running problems I deal with are related to phase seperation of E-10 fuel. Honda and Briggs & Stratton do not recommend using fuel over 30 days old.
    This can be avoided by using a fuel stabilizer immediately upon fueling. Adding stabilizer to "bad" fuel will not make it "good," however. If you are running a two-stroke, check to see if the oil that you use (pre-mix only) has stabilizer "built-in." Hope this helps.

  20. #20
    Lieutenant Commander Beefer's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by Fed View Post
    80 Gallons is only 0.3028329 cubic metres, how many grams of water can you wring out of that and how many times can you wring it out.
    Of course your arguement assumes the temperature inside the tank drops to the ambient outside temperature as well.

    If condensation was causing water problems inside fuel tanks the seas would be awash with dead boats and the roads would be littered with dead cars.
    I'm not going to argue with you. Obviously it would be about 1/3 of the 11g, so it would take a little longer. You go on believing what you want.
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  21. #21
    Admiral dingbat's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by Beefer View Post
    I'm not going to argue with you. Obviously it would be about 1/3 of the 11g, so it would take a little longer. You go on believing what you want.
    You’re completely ignoring the evaporation process in your theory. If a thunder storm comes through each afternoon and drops a 1/4" of rain each time, would you there be 1.75" of rain on your drive at the end of the week?

    We all know that is not true. As soon as the "condensation" cycle ends, the evaporation cycle begins. Condensation and evaporation cycles keep thing in equilabrium. Ignoring the process is a major flaw in your hypothesis.

    I have already posted two government studies that refute your condensation theory. Both say it's chemically impossible to condensate more water than the fuel saturation point.

    If you can point me to some studies done by reputable organizations or firms to support hypothesis, I’d like to see them.
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  22. #22
    Rear Admiral oldjeep's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by Rezqewr View Post
    E-10 ethanol fuel begins to separate the second it leaves the pump. My current job is working in a small engine shop, and 90% of the running problems I deal with are related to phase seperation of E-10 fuel. Honda and Briggs & Stratton do not recommend using fuel over 30 days old.
    This can be avoided by using a fuel stabilizer immediately upon fueling. Adding stabilizer to "bad" fuel will not make it "good," however. If you are running a two-stroke, check to see if the oil that you use (pre-mix only) has stabilizer "built-in." Hope this helps.
    We must get the magic blend of E-10 here in MN. Never had an issue - especially in something like a lawnmower/chainsaw which will run on whatever crap you have available. The common way to get rid of bad/old gas around here is to use it in your lawnmower. (Current batch of lawnmower gas came out of a 78 F150 that had been sitting for 3 years)
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  23. #23
    Lieutenant Commander Beefer's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by dingbat View Post
    You’re completely ignoring the evaporation process in your theory. If a thunder storm comes through each afternoon and drops a 1/4" of rain each time, would you there be 1.75" of rain on your drive at the end of the week?

    We all know that is not true. As soon as the "condensation" cycle ends, the evaporation cycle begins. Condensation and evaporation cycles keep thing in equilabrium. Ignoring the process is a major flaw in your hypothesis.

    I have already posted two government studies that refute your condensation theory. Both say it's chemically impossible to condensate more water than the fuel saturation point.

    If you can point me to some studies done by reputable organizations or firms to support hypothesis, I’d like to see them.
    So you're saying that condensation just doesn't exist in nature? Evaporation keeps it in check, and it just doesn't happen? So the hundreds of boaters that are having phase separation problems, and water in their fuel are having those problems because they are, what, adding water? Where does the evaporated moisture go? Out the vent? For that to happen, I believe the atmospheric pressure inside the tank would have to be greater then the pressure outside.

    Oh, and there are lots of special interest groups and lobbyists that *may* sway some governmental findings. Just saying, and let's keep the government and politics out of this.

    There are tons of threads about water related issues in E10 and phase separation on numerous sites, and I think it's reasonable to say that it is a real issue out there.
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  24. #24
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    Default Re: Ethanol Fuel Seperation Problems

    My first boat sat for nearly 2 years without being run due to things I could not control, I used highway gas, ethanol mix, in that boat. When I got ready to use it again I did a tune up and fuel filter change, new battery, chased a couple electrical problems and started the engine on the muffs, ran it about 20 min and then put it in the water and ran it there, it ran fine. That boat was always stored with a full gas tank, I did not use any treatments other than an occasional bottle of stp gas treatment, nothing to prevent anything from happening. If ethanol gas was going to separate as bad as some would have you believe that gas would separated. I personally do not think that ethanol gas separates that bad, now should you get water in your tank then things can happen, if you store the boat with a full tank of gas then condensation is not a problem. My current boat is stored with a full tank of gas, I do use the regular Stabil now and an occasional can of Sea Foam, I still have no problems. Just my thoughts from personal experience.
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  25. #25
    Lieutenant Commander Beefer's Avatar
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    Default Re: Ethanol Fuel Seperation Problems

    Quote Originally Posted by nlain View Post
    My first boat sat for nearly 2 years without being run due to things I could not control, I used highway gas, ethanol mix, in that boat. When I got ready to use it again I did a tune up and fuel filter change, new battery, chased a couple electrical problems and started the engine on the muffs, ran it about 20 min and then put it in the water and ran it there, it ran fine. That boat was always stored with a full gas tank, I did not use any treatments other than an occasional bottle of stp gas treatment, nothing to prevent anything from happening. If ethanol gas was going to separate as bad as some would have you believe that gas would separated. I personally do not think that ethanol gas separates that bad, now should you get water in your tank then things can happen, if you store the boat with a full tank of gas then condensation is not a problem. My current boat is stored with a full tank of gas, I do use the regular Stabil now and an occasional can of Sea Foam, I still have no problems. Just my thoughts from personal experience.
    How long ago? You say it was your first boat. May have been before E10 was introduced in your area, so it may not be applicable. If it was stored with a full tank, then there is no air volume to allow for the condensation. The problem is when tanks are not filled up that the condensation can occur, resulting in the problems. I give up. You guys are right, E10 is great for your boats, and their engines, and you'll never have a problem related to it. Just leave in the older grey fuel lines, and happily run E10 through it, leave your boats stored with a half tank of untreated E10 for a year or two, and go play. May God be with you, and make sure you have towing coverage. I'm done.
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